Emerging Insect Pests in the Pacific Northwest

Michael R. Bush, Christopher Adams, and Sven Spichiger
Latest revision: 
March 2023

In this section

Non-native insect pests are species that have extended their range from their native habitat to a new area. This movement may be between continents, or within a continent. While non-native species may move on their own, often they arrive via commercial transportation activities. Some non-native insects adapt to new habitats or geographic areas without drawing attention, and cause no significant economic harm. Other newly arriving insects do cause damage to plants, structures, or to human health and are therefore recognized as “emerging pests”. In this section we will describe existing and emerging non-native insect pests.

While the damage caused by non-native insect pests may have obvious impacts, costs associated with these species can be much harder to calculate. The economic impact of non-native pests may include any of the following costs: increased use of pesticides and their non-target impacts; new rules and regulations; loss of overseas markets; education campaigns; monitoring efforts; management of quarantine areas; containment and eradication efforts; property damage and lost property taxes. These impacts can have further ramifications for agriculture, communities, the environment, and taxpayers. Science News (2011) reports that “non-native, wood-boring insects such as the emerald ash borer and the Asian long horned beetle exact an estimated $1.7 billion in local government expenditures, and approximately $830 million in lost residential property values each year.”

In the Pacific Northwest, most of our worst pests are non-native species introduced from other areas of the world, or in some cases, other areas of the United States. Examples include gypsy moth, Japanese beetle, black vine weevil, European crane fly, apple maggot, and San Jose scale. A list of introduced pests can be found on the website of your state department of agriculture:

Washington: https://agr.wa.gov/departments/insects-pests-and-weeds

Oregon: https://www.invasivespeciesinfo.gov/us/oregon

Idaho: https://agri.idaho.gov/main/tag/invasive-species/

This section of the Handbook includes information on new and existing insect pests to the Pacific Northwest. World trade has increased the number of new invasive species in our gardens, crops, and natural environment. If you find unfamiliar species, or pests causing damage to landscape plants, crops, structures, etc., please contact your state department of agriculture, your state invasive species council (see below) or your local county extension office. In Washington, you can capture a series of digital images and send the best photos to PestProgram@agr.wa.gov for identification.

For further information:

Rosetta, R. L. 2017. An Update on New and Emerging Pests in the Pacific Northwest. https://www.publicgardens.org/resources/update-new-and-emerging-pests-pa...

Washington Invasive Species Council. 2019. Priority Species. https://invasivespecies.wa.gov/find-a-priority-species/

Oregon Invasive Species Council. https://www.oregoninvasivespeciescouncil.org/

Idaho Invasive Species Council. http://invasivespecies.idaho.gov/idaho-invasive-species-council

Aukema J. E., B. Leung, K. Kovacs, C. Chivers, K. O. Britton, J. Englin, S. J. Frankel, R. G. Haight, T. P. Holmes, A. M. Liebhold, D. G. McCullough, B. Von Holle. Economic Impacts of Non-Native Forest Insects in the Continental United States. PLoS ONE, 2011; 6 (9): e24587 DOI: 10.1371/journal.pone.0024587